1. Field of the Invention
The present invention relates to a radio communication system having a random access channel for the transmission of data from a secondary station to a primary station, and further relates to primary and secondary stations for use in such a system and to a method of operating such a system. While the present specification describes a system with particular reference to the emerging Universal Mobile Telecommunication System (UMTS), it is to be understood that the techniques described are equally applicable to use in other mobile radio systems. In this specifications the term random access channel refers to the logical channel on which random access transmissions take place, which would typically consist of a number of distinct physical channels.
2. Description of the Related Art
A random access channel is a normal component of a radio communication system, enabling a Mobile Station (MS) to send short messages to a Base Station (BS). Applications include signalling to the BS when the MS is turned on, sending a packet of data to the BS when the MS may not be engaged in a call, and requesting the BS to allocate a resource for the MS to use.
In a system where mobile stations often have a requirement to send packets of data to the BS when not actually engaged in a call it is advantageous to provide a random access packet channel with similar characteristics to a standard random access channel but intended for the transmission of small and medium sized packets from a MS to the BS.
In an embodiment of a scheme being developed for UMTS, there are a number of random access packet channels available to a MS. A request for access to a packet channel sent by the MS is encoded with a randomly-chosen signature, which corresponds to a packet channel resource. If a suitable channel is available for use, the BS allocates it to the requesting MS.
An object of the present invention is to provide a random access channel having improved resource utilization.
According to a first aspect of the present invention there is provided a radio communication system having a random access channel for the transmission of data from a secondary station to a primary station, wherein the secondary station has means for transmitting, before the transmission of the data, a message including an indication of the quantity of data to be transmitted and the primary station has means for determining from the received message when the data transmission will end.
According to a second aspect of the present invention there is provided a primary station for use in a radio communication system having a random access channel for the transmission of data from a secondary station to the primary station, wherein means are provided for receiving from the secondary station, before the transmission of the data, a message including an indication of the quantity of data to be transmitted, and for determining from the received message when the data transmission will end.
According to a third aspect of the present invention there is provided a secondary station for use in a radio communication system having a random access channel for the transmission of data to a primary station, wherein means are provided for transmitting, before the transmission of the data, a message including an indication of the quantity of data to be transmitted.
According to a fourth aspect of the present invention there is provided a method of operating a radio communication system having a random access channel for the transmission of data from a secondary station to a primary station, characterised by the secondary station transmitting, before the transmission of the data, a message including an indication of the quantity of data to be transmitted, and by the primary station determining from the received message when the data transmission will end. dr
Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, wherein:
FIG. 1 is a block schematic diagram of a radio communication system;
FIG. 2 illustrates a basic random access packet channel scheme;
FIG. 3 illustrates an enhanced random access packet channel scheme having a packet header;
FIG. 4 illustrates a further enhanced random access packet channel scheme having a packet channel availability message; and
FIG. 5 is a flow chart illustrating a method in accordance with the present invention for transmitting a packet header on a random access packet channel.
In the drawings the same reference numerals have been used to indicate corresponding features.